Electronic packages having leads arranged in a ball grid array (BGA) or a land grid array (LGA) are known. These packages have a relatively low height which is desirable for saving space in electronic assemblies. The packages may be surface mounted directly on a circuit board in a soldering process wherein the leads become solder bonded to a corresponding array of circuit pads on the board. However, solder bonding has the drawback that the package is not easily removable for replacement or upgrade. It is often desirable to provide a connector for mounting the electronic package on the circuit board in a separable fashion.
Connectors are known for removably mounting a BGA or LGA package on a circuit board. Such connectors are disclosed in U.S. Pat. No. 4,511,197; 4,513,353; 4,647,124; and 4,699,593. These connectors comprise a substantially flat dielectric housing which resides between the electronic package and the circuit board. The housing has an array of cavities in which are disposed electrical contacts arranged in correspondence with the array of leads of the electronic package. Each of the contacts has a pair of oppositely extending noses which project beyond external surfaces of the connector housing. When the package is mounted on the connector, each of the contacts has one nose engaged with a respective lead of the package and the other nose engaged with a respective pad on the board. A compressive force is applied to the package and the board to assure firm engagement of each nose with its respective lead or pad. Typically, the compressive force may be applied by pressure plates which are fastened together to sandwich the package, connector and board therebetween.
In packaging electronic components, consideration must be given to horizontal and vertical space limitations, and the nature of the assembly often dictates parameters on the space limitations. For example, in packaging lap top computers, vertical space is much more valuable than horizontal space. Design requirements for a future laptop computer call for a connector only 0.032 inch high and a working range of 0.015 inch. The working range is a very large percentage of the total connector height, thus making the contact design quite difficult. Accordingly, it is an object of the invention to provide a contact having a low overall height and a large working range.
Further, modern electrical equipment may operate at very high switching frequencies, and this can give rise to significant self-inductance effects which may interfere with proper operation of the equipment. Self-inductance effects can be reduced by reducing the length of the circuit path through the contact. However, it is desirable for the contact to have a relatively long spring arm to provide compliance which is necessary to permit deflection of the contact without plastic deformation. In order to overcome the problem posed by these competing interests, contacts have been developed with spring arms for compliancy and a shorting arm which interconnects free ends of the spring arms to provide a shorter current path through the contact. One such contact is disclosed in U.S. Pat. No. 4,354,729, wherein a shorting arm 68 has a side edge in sliding engagement with side edge 79 of latch arm 54. Contacts such as this are becoming increasingly miniaturized, and as the thickness of the contact is decreased, it becomes increasingly difficult to mate the side edges of arms 68 and 74. Accordingly, it is an object of the invention to lower the self-inductance effect in a contact made from very thin material.